Springs of the Belleville type have been used for various applications and constitute circular elements of spring steel having a generally frusto-conical shape with an inner periphery which is spaced axially from the plane of the outer spring periphery so that the force applied axially against the spring causes the inner periphery to move toward the outer periphery to place the spring under compression. This movement of the frusto-conical spring steel element in an axial direction causes the spring to generate a restoring force proportional to the applied load, which restoring force is not uniform over the relatively small movement of a frusto-conical spring. Belleville springs are used in many applications and are produced by the millions for a wide variety of mechanical devices, such as transmissions for automobiles, etc. Since Belleville springs are mass produced components, the reduction in the overall cost of manufacturing a Belleville spring, even if relatively small translates into substantial gross cost savings.
Belleville springs have heretofore been formed by blanking a flat, washer like, ring from a sheet of plain carbon steel that is normally cold rolled. After the flat ring of carbon steel is stamped or punched from the steel sheet or strip, it is pressed formed into a truncated conical shape by applying pressure through matching dies. The frusto-conical steel element is heated to a relatively high temperature, approaching 2,000.degree. F., and is subsequently quench hardened to create the spring characteristics in the frusto-conical element. Quench hardening is often followed by heating and cooling steps to stress relieve the spring, reduce distortions in the spring, obtain the desired final hardness and to set the spring into its final shape. This general manufacturing procedure is employed in making Belleville springs. The manufacture of such springs results in a considerable amount of scrap material, especially in larger sizes above about a 2.0 inches in diameter for the inner periphery, where the metal content of the Belleville spring is often 30-50% of the price of the spring itself Due to stamping of the ring shaped blank used in forming the Belleville spring from strip steel, the edges of the part have the normal burrs and shear marks. When the formed component is heat treated, the edges of the stamped sheet metal blank can become very brittle due to minute cracks. These cracks must be removed by costly and time consuming procedures, such as tumbling or grinding, which smooths the edges to increase the fatigue life of the Belleville spring. Thus, the amount of metal waste, the resulting burrs and stress cracks in the stamped edges of the spring and other problems experienced in manufacturing Belleville springs substantially add to the cost of these mass produced springs. The present invention relates to an improvement in manufacturing of Belleville springs, which improvement reduces scrap, avoids the deleterious effect of edge imperfections caused by stamping and heat treating and results in a Belleville spring having the desired technical parameters or characteristics.